[SDL] sensible optimization [was re: tile based _junk_]

Rafael R. Sevilla 94-22131 rsevilla at eee.upd.edu.ph
Mon Aug 23 13:26:12 PDT 1999

On Fri, 20 Aug 1999, Prasanth Kumar wrote:

> I read somewhere that movies can run at a low framerate because a video
> camera captures the blurring effect when an object moves fast compared to
> the camera speed. In a video game on the computer, the movement is discrete
> and so you need to crank up the framerate to compensate for the lack of
> blurring.

Movies can run at a low frame rate because the shutter on a physical movie
camera is open for a finite amount of time.  This effectively amounts to
applying a box filter in time to your movie, causing motion blur.  For
most computer animation, the "camera" has an effectively infinitesimal
shutter speed, and so the temporal aliasing effects are a lot more
pronounced and hence the animation becomes chunky.  We can approximate the
motion blur effect by determining how each pixel changes with time in
between frames and convolving that function with a filter of some sort to
get a final pixel value.  This process, or any one of several
approximations to it (postfiltering and stochastic sampling to name only a
few) are routinely done when generating high-quality computer animations, 
but I've never heard of it being done in real time, because it is clearly 
an expensive process.

| Rafael R. Sevilla                            rsevilla at eee.upd.edu.ph |
|           Instrumentation, Robotics, and Control Laboratory          |
|    College of Engineering, University of the Philippines, Diliman    |

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